Hot air is less dense than cold air and this is the reason that hot air balloons float! A hot air balloon on a cool summer morning is filled with air to a volume of 2.20 x 106 L and warmed to 195 °F (90 °C). A hot air balloon must be inflated to a volume of approximately 2.60 x 106 L in order to float in air.

a. (4 points) At constant pressure, provide a molecular-level explanation of the relationship between temperature and volume of a gas.

b. (6 points) Calculate the temperature the gas must be (in °C) in order to float.